Information recording method, information recording medium, and information reproducing method, wherein information is stored on a data recording portion and a management information recording portion

ABSTRACT

With this invention, at least one of a video file containing video information, a still picture file containing still picture information, and an audio file containing audio information and a management file having management information on a control method of reproducing the information in the file are recorded on an information storage medium. This realizes a data structure that causes the recording and deleting places on the information storage medium to correspond spuriously to places on a single tape, such as a VTR tape. Use of the data structure provides users with an easy-to-use interface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of application Ser. No. 10/195,789, filedJul. 16, 2002, which is a division of 09/651,295, filed Aug. 30, 2000,granted as U.S. Pat. No. 6,529,681, which is a division of applicationSer. No. 09/311,272, filed May 14, 1999, granted as U.S. Pat. No.6,341,196, the entire contents of each are hereby incorporated byreference. This application claims priority and contains subject matterrelated to Japanese Patent Application No. 10-133832, filed in theJapanese Patent Office on May 15, 1998, the entire contents of which ishereby incorporated by reference.

BACKGROUND OF THE INVENTION

This invention is concerned with the improvements in and relating to aninformation recording method of recording video information on aninformation storage medium and an information reproducing method ofreproducing the video information from the information storage medium,and more particularly to those suitable for a case where the videoinformation recorded on the information storage medium is the digitalvideo information compressed according to the MPEG (Moving Picture ImageCoding Experts Group) standards.

In recent years, systems for playing back an optical disk on which video(or moving picture) information and audio information have been recordedhave been developed. They have been widely used in the form of, forexample, LDs (Laser Disks) or video CDs (Compact Disks) for the purposeof reproducing movie software or karaoke.

In this connection, the DVD (Digital Versatile Disk) standard employingthe internationally standardized MPEG-2 scheme and the AC (AudioCompression)-3 or other audio compression schemes has been proposed. TheDVD standard covers playback-only DVD video (or DVD-ROM (Read-OnlyMemory)), write-once DVD-R (Recordable), rewritable DVD-RAM (RandomAccess Memory) (or DVD-RW (Rewritable)).

The DVD video (DVD-ROM) standard supports MPEG-2 for moving picturecompression scheme and not only liner PCM (Pulse Code Modulation) butalso AC-3 audio and MPEG audio for audio recording scheme.

The DVD video standard further supports sub-picture data obtained byrun-length compressing the bit map data for subtitles and reproducecontrol data (navigation data) for data searching by fast-forwardplayback or fast-rewind playback.

Furthermore, the DVD video standard supports ISO (InternationalOrganization for Standardization) 9660 and UDF (Universal Disk Format)to allow computers to read data.

For DVD video (DVD-ROM) optical disks, a 12-cm diameter single-sidedsingle-layer disk has a storage capacity of about 4.7 GB (Giga Bytes); a12-cm diameter single-sided double-layer disk has a storage capacity ofabout 9.5 GB; and a 12-cm diameter double-sided double-layer disk has astorage capacity of about 18 GB, provided that 650-nm (nanometers)wavelength laser light is used for reading.

On the other hand, for DVD-RAM (DVD-RW) optical disks, at the presenttime, a 12-cm diameter single-sided disk has a storage capacity of about2.6 GB and a 12-cm diameter double-sided disk has a storage capacity ofabout 5.2 GB. Namely, DVD-RAM optical disks in practical use have asmaller storage capacity than DVD-ROM disks of the same size.

In playback-only DVD video (DVD-ROM), like a hierarchical file structureused by a general-purpose computer operating system, the directorystructure of information (data files) recorded on an information storagemedium is such that a subdirectory of video title set VTS and asubdirectory of audio title set ATS are connected to a root directory asshown in FIG. 1.

In the subdirectory of video title set VTS, various video files(including VMGI, VMGM, VTSI, VTSM, and VTS) are so arranged that theindividual files can be managed in order. A specific file (for example,a specific VTS) can be accessed by specifying a path from the rootdirectory to the file.

Specifically, the root directory of a DVD video disk includes asubdirectory called video title set VTS. The subdirectory can containvarious management data files including VIDEO_TS.IFO orVTS_(—)01_(—)0.IFO, backup files, including VIDEO_TS.BUP andVTS_(—)01_(—)0.BUP, for backing up the information in those managementdata files, and a video data file VTS_(—)01_(—)1.VOB managed on thebasis of the contents of the management data files and used to storedigital video information. The subdirectory can also contain menu datafiles (including VMGM and VTSM) for storing specific menu information.

A DVD video disk is composed of a video manager VMG and at least one orup to 99 video title sets VTSS. The video manager VMG is composed ofcontrol data VMGI, VMG menu video object set VMGM_VOBS, and backupcontrol data VMGI_BUP. Each data is recorded on an information storagemedium as a single file.

As shown in FIG. 1, on the DVD video disk, the individual video titlesets (e.g., video title set VTS #1 and video title set VTS #2) have tobe recorded in separate files. In each video title set (e.g., videotitle set VTS #1), control data VTSI, VTS menu video object setVTSM_VOBS, and backup control data VTSI_BUP are recorded in separatefiles. Additionally, title video data VTS_(—)01_(—)1.VOB andVTS_(—)01_(—)2.VOB in the VTS are recorded in plural files.

The DVD-RAM disk uses a UDF file system, not a FAT (File AllocationTable) file system. The details of UDF will be described in detailslater. Like FAT, UDF enables a hierarchical structure of files andrecords data in files on an information storage medium. In the priorart, both of the UDF file and the FAT file are filled with data and haveno unrecorded area in them.

The contents will be explained in detail using one example. For example,when a statement has been written using word processor software (such asIchitaro, Word, or Amipro) running on a PC (Personal Computer), thewritten statement is recorded on an information storage medium as afile. In this case, all the file is filled with text data. Even if aspace area or a continues enter mark portion with no sentence continueslong in the middle of the written sentence, that portion in the storedfile will be filled with space data and enter data and therefore therewill be no fully unrecorded area in the file.

Even when the user reads the document file and stores the data afterdeleting the middle of the sentence, an unrecorded area is never definedin the stored information and is recorded on the information storagemedium as a file with the data items before and after the deletedportion putting together. As a result, the size of the file recorded onthe information storage medium decreases by the amount of data in thedeleted portion.

With application software running on an ordinary PC, a file read from aninformation storage medium for editing is transferred as it is to abuffer memory (semiconductor memory) on the PC. The edited data isstored temporarily in the buffer memory on the PC. Once the user hasgiven an instruction to store the file, the edited data stored in thebuffer memory on the PC is written over the whole file on theinformation storage medium. As described above, with the conventionalfile system, such as a FAT or UDF file system, when the file data ischanged, all the data in the file is changed at a time in the overwriteprocess. This is different from the present invention where the data inonly a part of the file is changed.

FIGS. 2A and 2B illustrate examples of reproducing video informationusing program chains PGCs on a DVD video disk. As shown in FIG. 2A, theplayback data is divided into cells and playback sections from cell A tocell F are specified. In the individual program chains PGC #1 to #3, PGCinformation is defined as shown in FIG. 2B. Specifically, the table inFIG. 2B reads as follows.

1. Program chain PGC #1 shows an example of being made up of cellsspecifying consecutive playback sections. The playback sequence is:

Cell A→Cell B→Cell C.

2. Program chain PGC #2 shows an example of being made up of cellsspecifying intermittent playback sections. The playback sequence is:

Cell D→Cell E→Cell F.

3. Program chain PGC #3 shows an example of being made up of cellsspecifying disorderly playback sections, regardless of the direction ofplayback or repetitive playback. The playback sequence is:

Cell E→Cell A→Cell D→Cell B→Cell E

By defining different program chains PGCs as described above, differentdisplay sequences can be realized for the same cells. In a DVD videodisk, all the cell information is not necessarily displayed by a singleprogram chain PGC because of the freedom of program chain PGC setting.

What has been explained above is about the data structure of the videoinformation recorded on a playback-only DVD video disk. An informationstorage medium capable of recording and reproducing video informationusing a DVD-RAM disk or a DVD-RW disk is now being developed as one formof the DVD family.

It is desirable that the video information recording format on theinformation storage medium capable of video recording and reproducingshould have a continuity and a relation with the data structure of a DVDvideo disk. In addition, a UDF file system is used for DVD-RAM disks orDVD-RW disks, as in the playback-only DVD video disk.

When the data structure of the aforementioned DVD video disk is useddirectly as the data structure on a recordable (video recordable)information storage medium and the above conventional UDF (or FAT) filesystem is used, the following problems arise:

1. Since the control data and video data are recorded in such a mannerthat they are distributed over plural files, when having deleted a fileby mistake, the user is unaware of the position of the error untiltrying to reproduce the deleted file in the course of playback. For theplayback-only DVD video disk, there is no possibility that the user willdelete a file. In the case of recordable/erasable information storagemediums, however, there is a danger that the user will delete a file bymistake.

2. Since the control data and video data are recorded in such a mannerthat they are distributed over plural files and the data structure hasthe same hierarchical structure as that of the computer data, it isdifficult for the family user unfamiliar with the computer to understandthe deleted place or the recorded place. Specifically, knowing only theVTR (Video Tape Recorder) as a medium capable of recording videoinformation, the family user wonders which part of the single tape theplace where the picture has been recorded or deleted has occupied.Therefore, showing the user small files of record or the result oferasing as they are would throw the user into confusion.

As shown in FIG. 1, in the DVD video disk, information is recorded insuch a manner that it is divided into separate files by video title setVTS. Thus, when plural video title sets (VTS#1 and VTS#2 in FIG. 1) havebeen recorded on the information storage medium, the user familiar withonly the VTR has no idea about the playback procedure.

3. With a method of allowing the family user to select a specific cellcorresponding to a program chain PGC for the recorded information, someuser is liable to fall into confusion. Specifically, knowing only theVTR as a medium capable of recording video information, the family userwill probably wonder which part of the single tape the place where thepicture has been recorded or deleted has occupied. Therefore, it wouldbe difficult for the user to understand the concept of selecting cellsby a program chain PGC on a playback-only DVD video disk.

4. In a data file recorded using the conventional UDF or FAT, there isno unrecorded area. Therefore, when part of a specific data item in afile has been deleted or a few pieces of video information have beenadded, the data items in front of and behind the deleted portion aresqueezed together and connected or the pieces of information are addedto the end of the existing data. Each time data is deleted or added, thesize of the whole data file has to be changed and all the changed datafile has to be recorded on the information storage medium again. As aresult, it take a very long time to complete the editing process.

Specifically, with the conventional UDF or FAT, since a file has nounrecorded area, the following processes cannot be carried out:

(a) The process of changing the erased place to an unrecorded area whenpart of the data in a file has been deleted.

(b) The process of recording additional data on an unrecorded area in afile without changing the entire file size.

Therefore, each time the data is deleted partially or added, the filesize has to be changed.

As a result, the entire file has to be recorded again on the informationstorage medium. In the case of a video file in which video informationhas been recorded, the size of a single video file is as large as morethan several hundreds of megabytes (MB). If a file as large as severalhundreds of megabytes is all recorded again on the information storagemedium each time a slight change has been made, it will take anextremely long time to change the contents of the file.

For a further description of the prior art, reference may be made to:

Japanese Patent Application No. 040876 (filed on Feb. 23, 1998)

Japanese Patent Application No. 040877 (filed on Feb. 23, 1998)

Japanese Patent Application No. 040879 (filed on Feb. 23, 1998).

BRIEF SUMMARY OF THE INVENTION

It is, accordingly, a first object of the present invention to overcomethe disadvantages in the prior art by providing an information recordingmethod for creating a data structure that causes a place whereinformation is recorded or deleted on an information storage medium tocorrespond spuriously to a place on a single tape, such as a VTR tape,in order to provide the family user familiar with only the VTR as amedium capable of recording video information with an easy-to-useinterface, and by providing an information reproducing method ofreproducing the recorded information.

A second object of the present invention is to provide an informationrecording method for creating a data structure that enables the generaluser to find the mistake readily even when having deleted a file bymistake and an information method of reproducing the information createdusing the data structure.

To achieve the foregoing objects, at least one of a video filecontaining video information, a still picture file containing stillpicture information, and an audio file containing audio information isrecorded on an information storage medium (e.g., an optical disk) in theinvention. Specifically, at least one of a video file, a still picturefile, and an audio file is recorded on an information storage medium onwhich information is recorded in files and from which the informationrecorded in a file can be read in a playback operation.

Furthermore, in the invention, a management file having managementinformation on a control method of reproducing all the informationrecorded in at least one of a video file, a still picture file, and anaudio file is recorded on an information storage medium (e.g., anoptical disk). Specifically, a management file having not only a seriesof links to reproduce all the information in the recording file but alsoplayback sequence information indicating the sequence for reproducingall the information recorded in the file is recorded on an informationstorage medium on which information is recorded in files and from whichthe information in a file can be read in a playback operation and onwhich at least one of a video file, a still picture file, and an audiofile has been recorded.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention, and together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1 is a diagram to help explain the structure of a conventionaldirectory for information (data files) recorded on an optical disk;

FIGS. 2A and 2B are diagrams to help explain the conventionalrelationship between cells and PGC information;

FIGS. 3A to 3H are related to an embodiment of the present invention andillustrate a hierarchical structure of information recorded on anoptical disk;

FIG. 4 is a diagram to help explain a directory structure of information(data files) recorded on an optical disk;

FIG. 5 is a diagram to help explain another directory structure ofinformation (data files) recorded on an optical disk;

FIG. 6 is a diagram to help explain still another directory structure ofinformation (data files) recorded on an optical disk;

FIG. 7 is a diagram to help explain the relationship between videoobjects and cells;

FIG. 8 is a diagram to help explain a data structure of cell timecontrol general information and cell time search information;

FIG. 9 is a diagram to help explain another data structure of cell timecontrol general information and cell time search information;

FIGS. 10A and 10B are diagrams to help explain the relationship betweencells and PGC information;

FIG. 11 is a block diagram of an information recording/reproducingapparatus for optical disks;

FIGS. 12A and 12B are diagrams to help explain an example of a filesystem constructed using a UDF;

FIGS. 13A and 13B are diagrams to help explain an example of a filesystem constructed using a UDF, by reference to FIGS. 12A and 12B;

FIG. 14 is a diagram to help explain the basic relationship between thehierarchical file system of FIG. 4 and the contents of the informationrecorded on the optical disk;

FIG. 15 is a diagram of a part of the file ID descriptor for describinginformation on files (including root directory, subdirectories, and filedata) in the file structure having the hierarchical structure of FIG. 4;

FIG. 16 is a diagram of a part of the contents of the file entrydescribing the recorded position of the specified file in the filestructure having the hierarchical structure of FIG. 4;

FIG. 17 is a diagram to help explain the contents of a short allocationdescriptor describing the recorded position of a consecutive sector set(extent) on an optical disk;

FIGS. 18A to 18D are diagrams to help explain a conventional method ofsetting file recording positions using a UDF;

FIGS. 19A to 19D are diagrams to help explain a method of setting filerecording positions using a UDF related to the present invention;

FIG. 20 is a diagram to help explain a data structure of the cell timegeneral information and cell VOBU table shown in FIG. 3H;

FIGS. 21A to 21D are diagrams to help explain the details of the data inthe video file shown in FIG. 4;

FIG. 22 is a diagram to help explain the details of the data in the VOBcontrol information shown in FIG. 3F;

FIGS. 23A to 23H are diagrams to help explain another example of ahierarchical structure of information recorded on an optical disk;

FIG. 24 is a diagram to help explain an example of a directory structureof information (data files) recorded on an optical disk using the datastructure shown in FIGS. 23A to 23H;

FIG. 25 is a conceptual diagram to help explain a case where a cellplayback sequence by the original PGC is changed by a user defined PGC;

FIG. 26 is a diagram to help explain a case where the original PGC iscomposed of plural programs;

FIG. 27 is a diagram to help explain the PGC information included in thenavigation data in FIG. 23D;

FIG. 28 is a diagram to help explain the details of the PGC generalinformation in the PGC information;

FIG. 29 is a diagram to help explain the details of the programinformation in the PGC information;

FIG. 30 is a diagram to help explain the details of the program type inthe program information;

FIG. 31 is a diagram to help explain the details of the thumbnailpointer information in the program information;

FIG. 32 is a diagram to help explain a still picture VOB group S_VOG forthumbnail points in the thumbnail pointer information;

FIG. 33 is a diagram to help explain the details of the cell informationsearch pointer in the PGC information;

FIG. 34 is a diagram to help explain the details of the cell informationin the PGC information;

FIG. 35 is a diagram to help explain the details of the movie cellinformation in the cell information;

FIG. 36 is a diagram to help explain the details of the movie cellgeneral information constituting the movie cell information; and

FIG. 37 is a diagram to help explain the details of the cell type in themovie cell general information.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an embodiment of the present invention will be explained byreference to the accompanying drawings. Using FIGS. 3A to 3H, the datastructure of video information recorded on an information storage mediumby an information recording method of the present invention will beexplained. FIG. 3A is a perspective view of an optical disk 1001 servingas an information storage medium.

FIG. 3B shows a rough data structure of information recorded on theoptical disk 1001. In FIG. 3B, a lead-in area 1002, volume & filemanager information 1003, a data area 1004, and a lead-out area 1005 arearranged in that order from the inner circumference side 1006 to outercircumference side 1007 of the optical disk 1001.

The lead-in area 1002 has an embossed data zone where the lightreflecting surface is uneven, a mirror zone where the surface is flat(mirrorlike), and a rewritable data zone where information can berewritten.

In the volume & file manager information 1003, information on all of theaudio & video data files or volumes is recorded in a rewritable datazone where the user can record or rewrite data.

The data area 1004 has a rewritable data zone where the user can recordor rewrite data. The lead-out area 1005 is made up of a rewritable datazone where information can be rewritten.

In the embossed data zone of the lead-in area 1002, the following piecesof information have been recorded beforehand: information on the disktype, such as DVD-ROM/-RAM/-R, the disk size, and the recording density,information on all of the information storage medium, including physicalsector numbers indicating the recording start/recording end positions,information on recording, reproducing, and erasing characteristics,including the recording power, recording pulse width, erasing power,reproducing power, and linear velocity in recording or erasing, andinformation on the manufacture of individual information storagemediums, including serial numbers.

Each of the rewritable zone in the lead-in area 1002 and that in thelead-out area 1005 has a disk name recording area for each informationstorage medium, a trial recording area (for checking the recording anderasing conditions), and a management information recording area fordefective areas in the data area 1004. An information recording andreproducing apparatus can record information on each of those areas.

In the data area 1004 sandwiched between the lead-in area 1002 and thelead-out area 1005, computer data and audio & video data can be recordedin such a manner that they are intermingled as shown in FIG. 3C. Theorder in which computer data and audio & video data are recorded and therecording information size of them are arbitrary. The areas in whichcomputer data is recorded are called computer data areas 1008, 1010. Thearea in which audio & video data is recorded is called an audio & videodata area 1009.

As shown in FIG. 3D, the data structure of information recorded in theaudio & video data area 1009 includes control information 1011 necessaryto perform each of video recording (audio recording), reproducing,editing, and retrieving processes, a video object 1012 of videoinformation on the contents of the video data, a picture object 1013 ofinformation on thumbnails for retrieving the desired one of the stillpictures, including slides, or the desired part of the video data or onthumbnails for editing, and an audio object 1014 of information on therecording of the contents of audio data.

As shown in FIG. 3E, the contents of the control information 1011include AV data control information 1101 that controls the datastructure of the video object 1012 and is management information aboutinformation on the recording position on an optical disk 1001 serving asan information storage medium, playback control information 1021 servingas control information necessary in playback, recording controlinformation 1022 serving as control information necessary in recording(video recording and audio recording), edit control information 1023serving as control information necessary in editing, and thumbnailpicture control information 1024 serving as management information onthumbnails (thumbnail pictures) for retrieving the desired portion ofthe video data or for editing.

As shown in FIG. 3F, the data structure of the AV data controlinformation 1101 includes PGC control information 1103 serving asinformation on video information playback programs (sequence) and celltime control information 1104 serving as information on the datastructure used as an audio information basic unit.

What has been described above is a general view of FIGS. 3A to 3F. Somesupplementary explanation will be given about each piece of information.In the volume & file manager information 1003, information on all thevolume and information on the number of files of contained PC data, thenumber of files of AV data, and recording layer information arerecorded.

The following are recorded as the recording layer information: thenumber of component layers (e.g., a single RAM/ROM two-layer disk iscounted as two layers, a single ROM two-layer disk is counted as twolayers, and an n number of single-sided disks are counted as n layers),a logical sector number range table allocated to each layer (a capacityfor each layer), characteristics for each layer (e.g., a DVD-RAM disk,the RAM section of a RAM/ROM two-layer disk, a CD-ROM, and a CD-R), alogical sector number range table allocated in zones in the RAM area foreach layer (including information on the capacity of the rewritable areafor each layer), and ID (Identifier) information unique to each layer(to find disk replacement in the multiple-disk pack). The recordinglayer information makes it possible to set consecutive logical sectornumbers to a multiple-disk pack or a RAM/ROM two-layer disk to create asingle large volume space.

Furthermore, the following are recorded in the playback controlinformation 1021: information on a playback sequence for the integrationof program chains PGCs, the original PGC information (corresponding to2213 in FIG. 23E or the original PGC in FIG. 25) or the information (thesequence for reproducing all the recorded cells consecutively)indicating spurious recording positions when an information storagemedium is regarded as a single tape, such as a VTR or a DVC (DigitalVideo Cassette), information on simultaneous playback of plural screenswith different pieces of video information, and retrieval information(that causes the corresponding ID and the start time table in the cellto be recorded for each retrieval category and enables the user toselect a category and access the video information directly).

Moreover, in the recording control information 1022, program reservedrecording information is recorded. In addition, the following arerecorded in the edit control information 1023: special edit informationin program chains PGCs (where the relevant time set information andspecial edit content are written as EDL information), and fileconversion information (the information to convert a specific part of anAV file into a file capable of special editing on a PC, such as an AVI(Audio Video Interleaving) file and specify a place to store theconverted file.

FIG. 4 shows a directory structure having only one video file on asingle information storage medium of the present invention. Therecording/reproducing video data itself in the video object 1012 of FIG.3D is recorded in the only video file RWVIDEO_OBJECT.VOB of FIG. 4.

The recording/reproducing video management data in the controlinformation 1011 of FIG. 3D is recorded in a file RWVIDEO_CONTROL.IFOand its backup file RWVIDEO_CONTROL.BUP shown in FIG. 4.

The RWVIDEO_CONTROL.BUP is updated each time the contents ofRWVIDEO_CONTROL.IFO is updated. In the reproducing, additionalrecording, partial deleting, or editing of ordinary video information,the RWVIDEO_CONTROL.IFO is used as recording/reproducing videomanagement data. Recordable information storage mediums, such asDVD-RAMs, are more liable to be affected by dust or a flaw on or in thesurface of the information storage medium in a playback operation thanin a recording operation. Therefore, when there is dust or a flaw on orin the surface, even if the information in the RWVIDEO_CONTROL.IFO hasbeen read accurately, the dust or flaw might sensitively affect therewriting (or recording) of the information in the RWVIDEO_CONTROL.IFO,making it impossible to update the contents. To overcome this problem,not only the RWVIDEO_CONTROL.IFO containing the management data but alsoRWVIDEO_CONTROL.BUP containing the same contents as those of theRWVIDEO_CONTROL.IFO are recorded on a recordable information storagemedium. This increases the reliability of the recording/reproducingvideo management data.

The information in the picture object 1013 of FIG. 3D is divided intostill picture data and thumbnail picture data, which are recorded in afile RWPICTURE_OBJECT.POB and a file RWTHUMNAIL_OBJECT.POB shown in FIG.4. The audio object 1014 of FIG. 3D is recorded in a fileRWAUDIO_OBJECT.AOB shown in FIG. 4.

The individual files related to a DVD video disk as shown in FIG. 1 arerecorded under a subdirectory of video title set VIDEO_TS shown in FIG.4, although not shown in the figure. According to the information inRWVIDEO_CONTROL.IFO (recording/reproducing video management data), theyare linked with RWVIDEO_OBJECT.VOB (recording/reproducing video data) toenable seamless, continuous playback of them.

FIG. 5 shows another example of the present invention. Specifically,video data, still picture data, thumbnail data, and audio data are allrecorded in a single file RWOBJECT.OB. Although all the data forrecording and reproducing is recorded in a file, the RWVIDEO_CONTROL.IFO(recording/reproducing video management data) in which the managementinformation including the playback procedure is recorded is recorded ina separate file.

FIG. 6 shows another embodiment of the present invention. Unlike theembodiment of FIG. 5, the embodiment of FIG. 6 is such that the videorecording/reproducing data including management data is all recorded ina single file RWAVFILE.DAT (Rewritable Audio Video File). In this case,the file RWAVFILE.DAT is placed not under a specific subdirectory butjust under the root directory.

Next, using FIG. 7, the relationship between video objects VOBs andcells will be explained. As shown in FIG. 7, each cell 84 is made up ofmore than one video object unit VOBU 85. Each video object unit VOBU 85is a collection (a pack train) of a VOBU begin pack 86, video packs (Vpacks) 88, sub-picture packs (SP packs) 90, and an audio pack (A pack)91 in that order, with the VOBU begin pack 86 at the head.

In the VOBU begin pack 86, the time that the video object unit VOBU 85was recorded on the information storage medium has been recorded in theform of year, month, day of the month, hours, minutes, and seconds. Withthe recorded time written in the VOBU begin pack 86, when the videoobject unit VOBU 85 is reproduced, the recorded time reproduced iscompared with the date and time that the relevant cell time of FIG. 20was created or last updated. This makes it possible to check in realtime whether the video object unit VOBU 85 currently being reproducedcoincides with the video object unit VOBU 85 specified in the cell timegeneral information #m 1116.

As described above, the reliability of the data in playback can beincreased by placing the VOBU begin pack 86 at the beginning of thevideo object unit VOBU 85 and recording the recorded time in the VOBUbegin pack 86. Moreover, in the VOBU begin pack 86, information relatedto the video object unit VOBU 85 automatically created in themicrocomputer block 30 of the information recording/reproducingapparatus of FIG. 11 can be recorded. Information used by theinformation recording/reproducing apparatus is recorded as theinformation related to the video object unit 85, which helps not onlyincrease the reliability of the reproduced video object unit VOBU 85 butalso improve the performance of the apparatus, such as the shortening ofthe access time. Furthermore, the video data program (EPG) and profileinformation on the video characters can be recorded as the informationrelated to the video object unit VOBU 85, which helps improve service tothe user during video data playback.

Specifically, the video object unit VOBU 85 is defined as a collectionof all the packs starting from a VOBU begin pack (navigation pack) 86 tothe one just before the next VOBU begin pack (navigation pack) 86. Thosepacks are used as the smallest units in transferring data. The smallestunit in logical processing is a cell. Logical processing is done incells.

The playback time of the video object unit VOBU 85 corresponds to theplayback time of the video data made up of more than one video group GOP(Group of Picture) contained in the video object unit VOBU 85. Theplayback time is set to the range from 0.4 second to 1.2 seconds. In theMPEG standard, the playback time of one GOP is normally about 0.5second. One GOP contains screen data compressed so that about 15pictures may be reproduced in about 0.5 second.

When a video object unit VOBU 85 includes video data, GOPs (complyingwith the MPEG standard) composed of video packs 88, sub-picture packs90, and audio packs 91 are arranged to produce a video data stream. Thevideo object unit VOBU 85 is determined on the basis of the playbacktime of the GOPs, regardless of the number of GOPs. At the head of thevideo object unit VOBU 85, a VOBU begin pack 86 is always placed asshown in FIG. 7.

Even when the playback data contains only audio and/or sub-picture data,it is constructed using a video object unit VOBU 85 as one unit. Forexample, when a video object unit VOBU 85 is made up of only an audiopack 91, with a VOBU begin pack 86 at the head, the audio pack 91 to bereproduced within the playback time of the video object unit VOBU 85 towhich the audio data belongs is stored in the video object unit VOBU 85,as in the video object VOB 83 of video data.

In an information recording and reproducing apparatus capable ofrecording on an information storage medium a video title set VTSincluding a video object set VOBS 82 of the structure as shown in FIG.7, the user often wants to edit the contents of the recording afterhaving recorded the video title set VTS. To meet the desire, dummy packs89 are allowed to be inserted in each video object unit VOBU 85. Thedummy pack 89 can be used later to record editing data.

As shown in FIG. 7, a video object set VTSTT_VOBS 82 is a set of morethan one video object VOB 83. The video objects VOBs 83 in a videoobject set VOBS 82 are used for the same application.

A video object set VOBS 82 for menus is normally made up of one videoobject VOB 83, in which plural menu screen display data items arestored. In contrast, a video object set VOBS 82 for title sets isnormally made up of plural video objects VOBs 83.

When a concert video for a certain rock band is taken as an example,video objects VOBs 83 constituting a video object set VTSTT_VOBS 82 fortitle sets can be considered as corresponding to the video data for theperformance of the band. In this case, by specifying the video objectsVOBs 83, for example, the third piece on the band's concert program canbe reproduced.

In the video objects VOBs 83 constituting a video object set VTSM_VOBSfor menus, the menu data for all the pieces of the band's concertprogram is stored. According to the menu on the screen, a specific pieceof music, for example, an encore, can be reproduced.

In an ordinary video program, one video object set VOBS 82 can becomposed of one video object VOB 83. In this case, one video stream iscompleted with a single video object VOB 83.

On the other hand, for example, in the case of a collection ofanimations with multiple stories or omnibus movies, plural video streams(plural program chains PGCs) can be provided for each story in one videoobject set VOBS 82. In this case, each video stream is stored in thecorresponding video object VOB 83. At that time, the audio stream andsub-picture stream related to each video stream are also completed ineach video object VOB 83.

Each video object VOB 83 is assigned an identification number IDN #j(j=1 to j). By the identification number, the video object VOB 83 can beidentified. A video object VOB 83 is composed of one or more cells 84.An ordinary video stream is made up of plural cells. A video stream formenus may be composed of one cell 84. Like the video object VOB 83, eachcell 84 is assigned an identification number IDN #j (i=1 to j).

The cell time control information 1104 of FIG. 3F is composed of celltime control general information 1111, cell time search information1112, and one or more pieces of cell time information 1113 to 1115 asshown in FIG. 3G.

Of these, the pieces of cell time information 1113 to 1115 each havecell time general information 1116 and a cell VOBU table 1117 as shownin FIG. 3H. The data structure of the cell time control generalinformation 1111 and that of the cell time search information 1112 areshown in FIGS. 8 and 9, the details of which will be explained later.

The playback sequence of the program chain (PGC) control information1103 of FIG. 3F is determined by a program chains PGC and cells. Theprogram chain PGC is a unit to execute a series of playback specifyingthe order in which cells are reproduced. A cell is a playback sectionspecifying playback data by a start address and an end address.

The program chain (PGC) control information 1103 is composed of PGCinformation management information, one or more pieces ofsearch-pointer-of-PGC information, and PGC information.

The PGC information management information includes information(number-of-PGCs information) on the number of program chains PGCS. Thesearch-pointer-of-PGC information points at the head of each PGCinformation and makes it easy to search.

The PGC information includes PGC general information and one or morepieces of search-pointer-of-cell-time information. The PGC generalinformation includes the playback time of program chains PGCs andinformation on the number of cells (search-pointer-of-cell-timeinformation). In the search-pointer-of-cell-time information, thepositions of the pieces of cell time information 1113 to 1115 arewritten.

An example of reproducing video information using a program chain PGC ina conventional DVD video has been explained in FIGS. 2A and 2B. In theconventional example, all the video information (all the cells) is notnecessarily reproduced continuously using a single program chain PGC.Since video information has been recorded in DVD video, the reproducingmethod of FIGS. 2A and 2B will not give the user a sense of incongruity.

In a video file of the present invention in which the user can recordpictures, the user records video information. With the reproducingmethod as explained in FIGS. 2A and 2B, the user familiar with the VTRis liable to fall into confusion about the relationship between thetotal video recording time and the remaining time.

On the other hand, with the present invention, the playback sequence isdetermined in a single program chain PGC so that all the videoinformation in a video file may be reproduced continuously as shown inFIGS. 10A and 10B. As shown in FIG. 10A, on an information storagemedium, video objects VOBs are arranged from the inner circumferenceside of the disk in this order:

VOB_IDN #1→VOB_IDN #3→VOB_IDN #2.

According to this arrangement, cells are arranged from the innercircumference side of the disk in this order:

cell A→cell B→cell C→cell F→cell G→cell D→cell E.

In contrast, a program chain PGC indicating the sequence in which allthe cells shown in FIG. 10B are reproduced consecutively reproducescells in this order:

cell A→cell B→cell C→cell D→cell E→cell F→cell G.

FIG. 11 shows the configuration of an information recording/reproducingapparatus which records and reproduce information on and from aninformation storage medium having video files shown in FIG. 1 or 4. Theinformation recording/reproducing apparatus comprises the following maincomponent parts: an information recording/reproducing section 32 thatrotates an optical disk 1001 acting as an information storage mediumhaving video files and reads and writes information from and onto theoptical disk 1001, an encoder section 50 constituting the videorecording side, a decoder section 60 constituting the reproducing side,and a microcomputer block 30 that controls the operation of the mainpart of the apparatus.

The encoder section 50 includes an ADC (Analog Digital Converter) 52, aV (Video) encoder 53, an A (Audio) encoder 54, an SP (Sub-picture)encoder 55, a formatter 56, and a buffer memory 57.

The ADC 52 receives an external analog video signal+an external analogaudio signal from an AV input section 42 or an analog TV signal+ananalog audio signal from a TV (Television) tuner 44. The ADC 52 convertsthe inputted analog video signal into a digital signal at, for example,a sampling frequency of 13.5 MHz, with the number of quantization bitsbeing eight. Specifically, luminance component Y, color differencecomponent Cr (or Y−R), and color difference component Cb (or Y−B) areeach quantized in eight bits.

Similarly, the ADC 52 converts the inputted analog audio signal into adigital signal at, for example, a sampling frequency of 48 KHz, with thenumber of quantization bits being 16.

When the analog video signal and digital audio signal are inputted tothe ADC 52, the ADC 52 allows the digital audio signal to pass through.The ADC 52 may reduce only jitters incidental to the digital audiosignal or change the sampling rate or the number of quantization bitswithout changing the contents of the digital audio signal.

On the other hand, when the digital video signal and digital audiosignal are inputted to the ADC 52, the ADC 52 allows the digital videosignal and digital audio signal to pass through. In this case, too, theADC 52 may reduce jitters or change the sampling rate without changingthe contents of the digital video signal and digital audio signal.

The digital video signal outputted from the ADC 52 is sent to theformatter 56 via the V encoder 53. The digital audio signal outputtedfrom the ADC 52 is sent to the formatter 56 via the A encoder 54.

The V encoder 53 has the function of converting the inputted digitalvideo signal into a digital signal compressed at a variable bit rateaccording to the MPEG-2 or MPEG-1 standard.

The A encoder 54 has the function of converting the inputted digitalaudio signal into a digital signal compressed at a fixed bit rate or alinear PCM digital signal according to the MPEG or AC-3 standard.

When the sub-picture information is inputted from the AV input section42 (e.g., the signal from a DVD video player with an independent outputterminal for sub-picture signal), or when a DVD video signal with such adata structure is broadcast and then received by the TV tuner 44, thesub-picture signal (sup-picture pack) in the DVD video signal isinputted to the SP encoder 55. The sup-picture signal inputted to the SPencoder 55 is arranged into a specific signal form, which is sent to theformatter 56.

The formatter 56 subjects the inputted video signal, audio signal, andsup-picture signal to specific processes using the buffer memory 57 as awork area and outputs the recording data conforming to the format (filestructure) explained in FIG. 7 to a data processor 36.

Here, a standard encode process for creating the recording data will beexplained briefly. In the encoder section 50 of FIG. 11, when the encodeprocess is started, the parameters necessary to encode the video (mainpicture) data and audio data are set.

Next, by pre-encoding the main picture data using the set parameters,the distribution of the amount of codes best suitable for the setaverage transfer rate (recording rate) is calculated. In this way, theencoding process of the main picture data is executed on the basis ofthe amount-of-codes distribution calculated in the pre-encoding process.At that time, the encoding process of the audio data is executed at thesame time.

When the amount of data compression is insufficient as a result of thepre-encoding process (or when the desired video program does not fit inan information storage medium), if the pre-encoding process can beexecuted again (e.g., the video recording source is a repeatedlyreproducible source, such as video tape or a video disk), part of themain picture data is encoded again and the re-encoded part of the mainpicture data is replaced with the main picture data portion previouslypre-encoded. By such a series of processes, the main picture data andaudio data are encoded, thereby reducing remarkably the value of theaverage bit rate necessary for recording.

Similarly, the parameters necessary to encode the sup-picture data areset and the encoded sup-picture data is produced.

The encoded main picture data, audio data, and sup-picture data arecombined and formatted into the structure of the video title set VTS.

Specifically, a cell is set as the smallest unit of the main picturedata (video data). Then, the cell time information as shown in FIGS. 8and 9 is created as described later. Next, the structure of cellsconstituting a program chain PGC as shown in FIGS. 10A and 10B and theattributes of the main picture, sub-picture, and audio are set, therebycreating a recording/reproducing video management data fileRWVIDEO_CONTROL.IFO including various pieces of information.

The encoded main picture data, audio data, and sup-picture data aredivided into packs of a constant size (2048 bytes) as shown in FIG. 7.Dummy packs 89 are inserted in the packs whenever necessary. In thepacks other than the dummy packs 89, time stamps, including PTS(Presentation Time Stamp) and DTS (Decoding Time Stamp), are writtenwhenever necessary. For the PTS of a sub-picture, the time delayed anarbitrary time from the PTS of the main picture data or audio data inthe same playback time zone can be written.

Then, a VOBU begin pack (navigation pack) 86 is placed at the head,followed by cells, in a video object unit VOBU 85 unit, which therebycreates a video object VOB 83 composed of plural cells. One or more ofthe video object VOB 83 are gathered together to form a video object setVOBS 82, which is recorded in the recording/reproducing video data fileRWVIDEO_OBJECT.VOB of FIG. 4.

When the DVD playback signal is digital copied from a DVD video player,the contents of the cells, program chains, management tables, and timestamps need not be created again, because they have been determinedalready. However, to construct a DVD video recorder so that it enables adigital copy of the DVD playback signal, electronic watermarks or othercopyright protecting means have to be provided.

A disk drive section that reads and writes (video records and/orreproduces) information from and onto an information storage medium (oroptical disk 1001) includes a disk changer section 100, an informationrecording/reproducing section 32, a temporary storage section 34, a dataprocessor 36, and an STC (System Time Counter or System Time Clock) 38.

The temporary storage section 34 is used to buffer a constant amount ofthe data (the data outputted from the encoder section 50) written ontoan information storage medium (optical disk 1001) via the informationrecording/reproducing section 32 or to buffer a constant amount of thedata (the data inputted to the decoder section 60) reproduced from theinformation storage medium (optical disk 1001) via the informationrecording/reproducing section 32.

For example, when the temporary storage section 34 is composed of a4-Mbyte semiconductor memory (D-RAM (dynamic RAM)), about eight secondsof recording or playback data can be buffered at a recording rate of anaverage of 4 Mbps (bit per second). When the temporary storage section34 is composed of a 16-Mbyte EEP (Electrically Erasable andProgrammable) ROM (flash memory), about 30 seconds of recording orplayback data can be buffered at a recording rate of an average of 4Mbps. Furthermore, when the temporary storage section 34 is composed ofa 100-Mbyte ultra-compact HDD (hard Disk Drive), about three minutes ormore of recording or playback data can be buffered at a recording rateof an average of 4 Mbps.

When the information storage medium (optical disk 1001) is used up inthe course of video recording, the temporary storage section 34 maystore temporarily the video information until the information storagemedium (optical disk 1001) has been replaced with a new one.

Furthermore, when a high-speed drive (a double-speed drive or fasterdrive) is used as the information recording/reproducing section 32, thetemporary storage section 34 can be used to store temporarily the dataread beyond the capacity of the ordinary drive within a specific time.Once the data read during playback has buffered in the temporary storagesection 34, even when the optical head (not shown) has made an error inreading due to vibrational shocks, use of the reproduced data bufferedin the temporary storage section 34 prevents the reproduced picturesfrom being interrupted.

Although not shown in FIG. 11, making an external card slot in theinformation recording/reproducing apparatus would enable the EEPROM tobe sold separately as an optional IC (Integrated Circuit) card.Moreover, providing the information recording/reproducing apparatus withan external drive slot or a SCSI (Small Computer System Interface) wouldenable the HDD to be sold separately as an optional extension drive.

Under the control of the microcomputer block 30, the data processor 36of FIG. 11 supplies the DVD recording data outputted from the encodersection 50 to the information recording/reproducing section 32, receivesthe DVD playback signal reproduced from the information storage medium(optical disk 1001) from the information recording/reproducing section32, rewrites the management information recorded on the informationstorage medium, or deletes the data (files or video title sets VTSs)recorded on the information storage medium.

The microprocessor block 30 includes an MPU (Micro Processing Unit) (ora CPU (Central Processing Unit)), a ROM in which control programs havebeen written, and a RAM for providing the necessary work area to executeprograms.

The MPU of the microcomputer block 30 uses the RAM as a work areaaccording to the control programs stored in the ROM and effects faultyplace sensing, unrecorded area sensing, video recording informationrecording position setting, UDF recording, AV address setting, andothers.

Of the results of execution by the MPU, the contents that should bereported to the user of the information recording/reproducing apparatusare displayed on either the display section 48 of the DVD video recorderor on the screen of a monitor display (OSD).

The timing for the microcomputer block 30 to control a disk changersection 100, the information recording/reproducing section 32, the dataprocessor 36, and the encoder section 50 and/or decoder section 60 maybe based on the time data from the STC 38. The recording and reproducingoperations are generally executed in synchronization with the time clockfrom the STC 38. The other processes may be executed with the timingindependent of the STC 38.

The decoder section 60 includes the following: a separator 62 thatseparates each pack from the video information having the pack structureof FIG. 7, a memory 63 used in executing the pack separation and othersignal processes, a V decoder 64 that decodes the main picture data (thecontents of the video packs 88 in FIG. 7) separated by the separator 62,an SP decoder 65 that decodes the sup-picture data (the contents of thesup-picture packs in FIG. 7) separated by the separator 62, an A decoder68 that decodes the audio data (the contents of the audio packs 91 inFIG. 7) separated by the separator 62, a video processor 66 thatcombines the main picture data from the V decoder 64 with thesub-picture data from the SP decoder 65 to superimpose sub-picturesincluding menus, highlight buttons, and subtitles on the main picture, aV-DAC 67 that converts the digital video output from the video processor66 into an analog video signal, and an A-DAC 69 that converts thedigital audio output from the A decoder 68 into an analog audio signal.

The analog video signal from the V-DAC 67 and the analog audio signalfrom the A-DAC 69 are supplied to an external component (a multi-channelstereo unit (e.g., a 2-channel to 6-channel stereo unit)+a monitor TV ora projector) (not shown).

The OSD display data from the microcomputer block 30 is inputted to theseparator 62 of the decoder section 60 and passes through the V decoder64 (which does not decode it). The OSD display data is then inputted tothe video processor 66. Then, the OSD display data is superimposed onthe main picture. The resulting picture is supplied to an externalmonitor TV connected to the AV output section 46. This enables a warningmessage to be displayed together with the main picture.

When a DVD-RAM disk is used as an information storage medium forrecording video files, the UDF is often used as a file format.Therefore, the contents of the UDF will be described by reference toFIGS. 12A to 17.

(A) Rough Explanation of UDF

(A-1) What is UDF?

UDF is an abbreviation of universal disk format. It shows the rule for afile management method mainly in a disk-like information storage medium.The CD-ROM, CD-R, CD-RW, DVD video, DVD-ROM, DVD-R, and DVD-RAM employthe UDF format standardized by ISO 9660.

The file management system is based on the assumption that ahierarchical file system which basically has a root directory as aparent and manages files in a tree-like manner. The UDF format chieflycomplying with the DVD-RAM standard (File System Specifications) will beexplained. Most part of the explanation below applies to the DVD-ROMstandard.

(A-2) Summary of UDF

(A-2-1) The Contents of File Information Recorded on an InformationStorage Medium

A collection of information is called file data. When information isrecorded on an information storage medium, recording is done in units offile data. To distinguish one collection of file data from another, eachcollection of file data is assigned a unique file name. Grouping pluralcollections of file data having the common contents of informationfacilitates file management and file retrieval. A group of collectionsof file data is called a directory or a folder. Each directory isassigned a unique directory name (or folder name).

Furthermore, plural directories (or folders) can be put together into ahigher-order directory (or higher-order folder) as a group at thepreceding level of hierarchy. Here, the file data and the directory(folder) are generically called files.

When information is recorded, the following pieces of information arerecorded on an information storage medium:

◯ The contents of collections of file data

◯ File name corresponding to each collection of file data

◯ Storage place of each collection of file data (under which directoryeach collection of file data is recorded).

In addition, the following pieces of information on each directory (orfolder) are recorded on the information storage medium:

◯ Directory name (of folder name)

◯ Position to which each directory (or folder) belongs (position of thehigher-order directory (or higher-order folder) serving as theirparent).

(A-2-2) Information Recording Format on an Information Storage Medium

All the recording area on the information storage medium is divided intological sectors using 2048 bytes as the smallest unit. All the logicalsectors are assigned logical sector serial numbers. When information isrecorded on the information storage medium, information is recorded inlogical sectors. The recording places on the information storage mediumare managed by the logical sector numbers of the logical sectors inwhich the information has been recorded.

As shown in FIGS. 12A, 12B, 13A and 13B, the logical sectors in whichinformation on the file structure 486 and file data 487 have beenrecorded are called logical blocks. The logical blocks are assignedlogical block numbers (LBNs) in connection with the logical sectornumbers (LSNs). The length of the logical block is set to 2048 bytes asthat of the logical sector is.

(A-2-3) An Example of a Simplified Hierarchical File System

FIG. 14 shows an example of a simplified hierarchical file system. MostOS file management systems, including UNIX, Mac OS, MS-DOS, Windows,have a tree-like hierarchical structure.

Each disk drive (e.g., when a single HDD is divided into pluralpartitions, each partition corresponds to each disk drive) has one rootdirectory 401 serving as a parent for all this disk drive. To the rootdirectory, subdirectories 402 belong. The subdirectories 402 containscollections of file data 403.

In addition to the example, there may be a case where a collection offile data 403 exists just under the root directory 401 or pluralsubdirectories 402 are connected in series to form a complexhierarchical structure.

(A-2-4) The Contents of File Management Information Recorded on anInformation Storage Medium

The file management information is recorded in logical blocks. Thecontents recorded in each logical block are chiefly the following:

◯ Descriptive statement FID (File Identifier Descriptor) IndicatingInformation on Files.

It describes the types of file and file names (such as the rootdirectory name, subdirectory names, and file data names). In the FID, adescriptive statement indicating the contents of the subsequentcollection of file data and the recorded place of the contents of thedirectories (that is, the recorded places of the FE corresponding therelevant file explained below) is also written.

◯ Descriptive statement FE (File Entry) indicating the recorded place ofthe contents of files

Places on an information storage medium on which information on thecontents of collections of file data and on the contents of directories(subdirectories) has been recorded are written.

FIG. 15 shows an excerpt of the descriptive contents of the fileidentifier descriptor. The details of it will be explained under (B-4)File identifier descriptor. FIG. 16 shows an excerpt of the descriptivecontents of the file entry. The details of it will be explained under(B-3) File entry.

The descriptive statement indicating the recorded places on theinformation storage medium uses a long allocation descriptor and a shortallocation descriptor of FIG. 17. The details of the short allocationdescriptor will be explained under (B-1-3) Short allocation descriptor.

As an example, the descriptive contents of information on the filesystem structure of FIG. 14 recorded on an information storage mediumare as follows:

◯ The contents of the root directory 401 are written in the logicalblock with logical block number 1.

In the example of FIG. 14, the root directory 401 contains only asubdirectory 402. As a result, information on the subdirectory 402 iswritten in a file identifier descriptor statement 404 as the contents ofthe root directory 401. Although not shown, information on the rootdirectory 401 itself is also written in a file identifier descriptorstatement in the same logical block.

Furthermore, in the file identifier descriptor statement 404 of thesubdirectory 402, the recorded place of the file entry statement 405 (inthe example of FIG. 14, the second logical block) indicating where thecontents of the subdirectory 402 are recorded is written in a longallocation descriptor statement (LAD (2)).

◯ In the logical block with logical block number 2, a file entrystatement 405 indicating the place in which the contents of thesubdirectory 402 are recorded is recorded.

In the example of FIG. 14, the subdirectory 402 contains onlycollections of file data 403. As a result, the recorded place of a fileidentifier descriptor statement 406 indicating information on thecollections of file data 403 is essentially written as the contents ofthe subdirectory 402.

Furthermore, in the short allocation descriptor statement in the fileentry statement, it is written that the contents of the subdirectory 402are recorded in the third logical block (AD(3)).

◯ The contents of the subdirectory 402 are recorded in the logical blockwith logical block number 3.

In the example of FIG. 14, the subdirectory 402 contains onlycollections of file data 403. As a result, information on thecollections of file data 403 are written in a file identifier descriptorstatement 406 as the contents of the subdirectory 402. Although notshown, information on the subdirectory 402 itself is also written in afile identifier descriptor statement in the same logical block.

Furthermore, in the file identifier descriptor statement 406 about thecollections of file data 403, the recorded place of the file entrystatement 407 indicating where the contents of the collections of filedata 403 (in the example of FIG. 14, they are recorded in the forthlogical block) are recorded is written in a long allocation descriptorstatement (LAD (4)).

◯ In the logical block with logical block number 4, a file entrystatement 407 indicating the place in which the contents 408, 409 of thecollections of file data 403 are recorded is recorded.

In the short allocation descriptor statement in the file entry statement407, it is written that the contents 408, 409 of the collections of filedata 403 are recorded in the fifth and sixth logical blocks ((AD(5),AD(6)).

◯ In the logical block with logical block number 5, information (a) 408on the contents of the collection of file data 403 is recorded.

◯ In the logical block with logical block number 6, information (b) 409on the contents of the collection of file data 403 is recorded.

(A-2-5) Method of Accessing File Data According to the Information Shownin FIG. 14

As explained briefly under (A-2-4) The contents of file managementinformation recorded on an information storage medium, in the fileidentifier descriptors 404, 406 and the file entries 405, 407, thelogical block numbers indicating the pieces of information that followthose contents are written.

Just as a collection of file data is reached via subdirectories,starting from the root directory and going down levels of hierarchy, thecontents of the collection of file data are accessed by reproducing thepieces of information in logical blocks on the information storagemedium in sequence according to the logical block numbers written in thefile identifier descriptor and file entry.

Specifically, to access the collection of file data 403 according to theinformation shown in FIG. 14, the first logical block information isfirst read. Since the collection of file data 403 exists in thesubdirectory 402, the first logical block information is searched forthe file identifier descriptor 404 of the subdirectory 402. After LAD(2) has been read, the second logical block information is readaccording to LAD (2).

Because only one file entry statement is written in the second logicalblock, AD (3) is read from the block and control goes to the thirdlogical block. The third logical block is searched for the fileidentifier descriptor 406 written about the collection of file data 403.Then, LAD (4) is read. According to LAD (4), control proceeds to thefourth logical block. Because only one file entry statement 407 iswritten in the fourth logical block, AD (5) and AD (6) are read and thelogical block numbers (5 and 6) in which the contents of the collectionof file data 403 are recorded is found.

The contents of AD (*) and LAD (*) will be explained in detail under (B)Concrete description of the contents of each descriptive statement inthe UDF.

(A-3) Features of the UDF

(A-3-1) Explanation of the Features of the UDF

The features of the UDF will be explained in comparison with the FATused in the HDD, FDD (Floppy Disk Drive), and MO (Magneto optics):

(1) The UDF has large minimum units (including the minimum logical blocksize and the minimum logical sector size) and suitable to record videoinformation or music information that has a large amount of informationto be recorded.

Specifically, the size of a UDF logical sector (block) is as large as2048 bytes, whereas the size of a FAT logical sector is 512 bytes.

(2) With the UDF, the file management information can be recorded in adistributed manner at arbitrary places on the disk, whereas with theFAT, a management table (file allocation table) for allocating files tothe information storage medium is recorded intensively in a local placeon the information storage medium.

Specifically, with the UDF, the recorded places on the disk concerningthe file management information and file data are written as logicalsector (block) numbers in the allocation descriptor.

With the FAT, the file management information is controlled centrally inthe file management area (file allocation table). Therefore, the FAT issuitable for an application that needs to change the file structurefrequently (particularly to rewrite frequently). Since the FAT isrecorded in a local place, it is easy to rewrite the managementinformation. Furthermore, since the recorded place of the filemanagement information (file allocation table) has been determined, therecording medium is required to have high reliability (e.g., have nodefective area).

Since, with the UDF, the file management information is distributed overthe disk, this leads to few great changes in the file structure.Therefore, the UDF is suitable for an application where new filestructures are added later (particularly a postscript application).Namely, In adding a file structure, the present file managementinformation has only to be changed in fewer places.

Since the recording places of the distributed file managementinformation can be specified arbitrarily, recording can be done avoidingcongenital defective portions. Recording the file management informationin arbitrary places also enables all the file management information tobe concentrated in one place, which is the advantage of the FAT.Consequently, the UDF can be considered to be a more versatile filesystem.

(B) Concrete Description of the Contents of Each Descriptive Statement(Descriptor) in the UDF

(B-1) Descriptive Statement of Logical Block Number

(B-1-1) Allocation Descriptor

As described under (A-2-4) The contents of file management informationrecorded on an information storage medium, a descriptive statement thatis part of a file identifier descriptor or a file entry and describesthe place (logical block number) in which the information following thatfile identifier descriptor or file entry is recorded is called aallocation descriptor. There are two types of allocation descriptor: along allocation descriptor and a short allocation descriptor.

(B-1-2) Short Allocation Descriptor

As shown in FIG. 17, in the length of extent 410, the number of logicalblocks is expressed in four bytes. In the position of extent 411, therelevant logical block number is expressed in four bytes. In thedescriptive statement, the description is simplified and written in AD(logical block number).

(B-2) Unallocated Space Entry

This is a descriptive statement that writes the unrecorded extentdistribution on an information storage medium in a short descriptor foreach extent and arranges the descriptors. It is used in a space table(see FIGS. 12A, 12B, 13A and 13B). Specifically, in this statement, adescriptor tag (representing the identifier for the contents of thedescription), an ICB tag (representing the file type), and the totallength of the allocation descriptor train (the total number of bytes infour bytes) are written. The file type=1 in the ICB tag means anunallocated space entry. The file type=4 means a directory and the filetype=5 means file data.

(B-3) File Entry

This is the statement explained under (A-2-4) The contents of filemanagement information recorded on an information storage medium. Asshown in FIG. 16, in this statement, the following are written: adescriptor tag 417 (representing the identifier for the contents of thedescription, 261 in this case), an ICB tag 418 (representing the filetype, its contents being the same as (B-2)), permission 419(representing information on permission to record, reproduce, and deletefor each user, mainly used for assuring file security), and anallocation descriptor 420 (writing the location in which the contents ofthe relevant file are recorded for each extent by placing shortallocation descriptors side by side).

(B-4) File Identifier Descriptor

This is the statement explained under (A-2-4) The contents of filemanagement information recorded on an information storage medium. Asshown in FIG. 15, in this statement, the following are written: adescriptor tag 421 (representing the identifier for the contents of thedescription, 257 in this case), file characteristic 422 (representingthe type of file, meaning one of parent directory, directory, file data,and file delete flag), an information control block 423 (the FE locationcorresponding to the file is written in a long allocation descriptor), afile identifier 424 (directory name or file name), padding 437 (dummyareas added to adjust the total length of the file identifierdescriptor, in all of which “0” is normally written).

There are two methods of managing the unrecorded locations on aninformation storage medium:

◯ Space Bit Map Method

A recorded flag or an unrecorded flag is set in a bit map manner for allthe logical blocks in the recording area on the information storagemedium using the space bit map descriptor 470 (see FIGS. 12A and 12B).

◯ Space Table Method

All the unrecorded logical block numbers are written as a list of shortallocation descriptors using the form of writing an unallocated spaceentry 471 (see FIGS. 12A and 12B).

In the embodiment, the two methods are written in FIGS. 12A, 12B, 13Aand 13B for the sake of explanation. Actually, however, both of themethods are hardly used (recorded on the information storage medium) atthe same time. Only one of the methods is used.

An outline of the contents of the principal directories written in FIGS.12A, 12B, 13A and 13B is as follows:

Beginning extent area descriptor 445 . . . Indicates the start positionof volume recognition sequence 444.

Volume structure descriptor 466 . . . Describes the contents of thevolume 444.

Boot descriptor 447 . . . Describes the contents of processing in a bootoperation.

Terminating extent area descriptor 448 . . . Indicates the end positionof the volume recognition sequence 444.

Partition descriptor 450 . . . Indicates the partition information(including size). As a general rule, the DVD-RAM has one partition pervolume.

Logical volume descriptor 454 . . . Describes the contents of thelogical volume.

Anchor volume descriptor pointer 458 . . . Indicates the recordedlocations of the main volume descriptor sequence 449 and reserve volumedescriptor sequence 467.

Reserved (00h bytes all) 459 to 465 . . . Records specific descriptors.To secure logical sector numbers, adjusting areas in all of which “0” isrecorded are provided between them.

Reserve volume descriptor sequence 467 . . . Serves as a backup area forthe information recorded in the main volume descriptor sequence 449.

Using FIGS. 18A to 18D, a file position setting method in a conventionalmethod that has no unrecorded area in a video file will be explained.Consider a case where two PC files and a single video file have beenrecorded in the data area 1004 on an information storage medium as shownin FIG. 18A. In FIGS. 18A to 18D, LBN means a logical block number.

When the LBNs at the start position of the individual files are A, F,and C, the recording positions on the file entry of a PC file areFE[AD(A)] and FE[AD(F)] respectively by using the notations in FIGS.12A, 12B, 13A and 13B or FIGS. 14 and 16. Since in FIG. 18A, video file#1 is recorded together in one place, this makes it possible to writeusing one extent. As a result, the file entry corresponding to the fileis FE[AD(C)].

Next, consider a case where the logical blocks with LBNs from D to E invideo file #1 are erased. With the conventional method, an unrecordedarea is not allowed to exist in a file. Therefore, the recorded place invideo file #1 on the information storage medium is divided into twoplaces, as shown in FIG. 18B.

As a result, since the extent describing the allocation (recordingpositions) of the video file is divided in two, the file entry for thevideo file is FE[AD(C), AD(E)]. Under the UDF, the continues recordingand playback of video information are not managed. At the stage in FIG.18B, the areas with the LBNs from D to E are considered as an unrecordedarea and the recording of another file into the area is permitted. Forthis reason, PC file #3 may be recorded in the unrecorded area as shownin FIG. 18C.

In a case where another piece of video information cannot be recorded inthe logical blocks with the LBNs from D to E, regardless of an attemptto record the piece of video information, it is recorded as video file#2, another video file, in the place with the LBNs starting at G, faraway from video file #1, as shown in FIG. 18D. Specifically, with theconventional method that permits no unrecorded area to exist, videofiles are scattered over the information storage medium. When all thevideo files are reproduced continuously, continuous playback isdifficult because of the access time of the optical head. Similarly,with the conventional method, continuos recording is difficult.

Using FIGS. 19A to 19D, a method, related to the present invention, ofsetting a file recording position on the information storage medium in acase where an unrecorded area is allowed to exist in a video file willbe explained. FIG. 19A corresponds to FIG. 18A. In the embodiment, whenthe logical blocks with the LBNs from D to E are erased, the file sizeof the video file does not change because video file #1 has anunrecorded area as shown in FIG. 19B. The file entry to the video fileremains unchanged, FE[AD(C)]. As a result, when a new PC file isrecorded, any PC file will not be inserted into video file #1, as shownin FIG. 19C.

Furthermore, when video information is additionally recorded by videorecording, the additional recording information is recorded in theunrecorded area with the LBNs from D to E. The unrecorded area thenchanges to an additional recording area. As described above, with theinformation recording/reproducing apparatus of FIG. 11, the file systeminformation about the UDF need not be changed each time a small part ofthe video information is erased or additional recording is done by videorecording. This facilitates the processing of the informationrecording/reproducing apparatus. Moreover, when the amount of videoinformation increases, the video file size becomes larger.

That is, the unrecorded area with the LBNs from B to C of FIG. 19C isabsorbed by video file #1. While the video file of FIG. 19C has only oneextent AD(C), the video file of FIG. 19D has an additional extent AD(A),providing a file entry of FE[AD(C), AD(B)].

Information about each cell of FIG. 10 is recorded in the cell timecontrol information 1104 as shown in FIG. 3F. As shown in FIG. 3G, itscontents is made up of the following:

Cell time information #1 1113 to #m 1115 . . . Information on each ofthe cells 1121 to 1124.

Cell time search information 1112 . . . Map information indicating theposition (AV address) in which the corresponding cell time informationis written when a specific cell ID is specified.

Cell time control general information 1111 . . . Information about allthe cell information.

Each piece of cell time information contains cell time generalinformation #m 1116 and cell VOBU table #m 1117 as shown in FIG. 3H.

FIG. 8 illustrates the data structure of the cell time information. Itis made up of the cell time control general information 1111 indicatingthe recording position of each cell 84 of FIG. 7 in therecording/reproducing video data RWVIDEO_OBJECT.VOB (corresponding tothe contents of the video object 1012 in FIG. 3D) and the cell timesearch information 1112 indicating the pieces of LBN (logical blocknumber) information 2011 to 2013 in the place where the cell timeinformation is recorded, in the recording/reproducing video managementdata RWVIDEO_CONTROL.IFO (corresponding to the data in the controlinformation 1011 of FIG. 3D).

In the cell time control general information 1111, writing is done inthe recording position using the AV address. While in FIG. 8, the AVaddresses 2002, 2004, 2006 at the begin positions and the respectivedata sizes 2003, 2005, 2007 are written as the positional informationfor each cell, the AV addresses 2023, 2025, and 2027 at the endpositions are written in place of data size in another example of FIG.9.

The contents of the cell time information recorded in therecording/reproducing video management data RWVIDEO_CONTROL.IFO (thesame as the data in the control information 1011 of FIG. 3D) of FIG. 4are shown in FIG. 20.

Specifically, the cell time general information 1116 indicates generalinformation on each cell. The playback speed 2033 is recorded for eachcell, enabling variable speed playback. For example, only the CM portioncan be played back at high speed.

Furthermore, the password 2034 and permission 2035 can be recorded incells, assuring security and enabling parental lock. The contents of thepermission setting for each cell are as shown in FIG. 20. Moreover, forthe erase level restorable by UNDO like the dustbin on a PC, the usercan set erase specify information 2036 or erase/overwrite priority rankinformation 2037 indicating the order of priority in which erasing isdone automatically according to the remaining amount in video recording.

The cell VOBU table 117 of FIG. 20 is used for time codes. Specifically,time codes are expressed by a combination of the number of video frames2042, 2044, 2046 contained in a cell and the data sizes (the number ofsectors used) for the respective individual VOBUs 2041, 2043, 2045. Useof this notation enables a time code to be expressed by a very smallamount of information. Hereinafter, an accessing method using the timecodes will be explained.

1. The user specifies the desired cell and the time at which the cell isto be accessed.

2. According to the specified time, the MPU of the microcomputer block30 of FIG. 11 calculates the video frame number from the cell startposition of the corresponding video frame.

3. The MPU calculates the cumulative total of the number of video frames2042 to 2046 for each VOBU from the cell head shown in FIG. 20 anddetermines which video frame in which VOBU the user-specified videoframe falls on, counting from the first VOBU.

4. The recording positions of all the data items in the cell on theinformation storage medium are determined from the cell time controlgeneral information of FIG. 8 or 9.

Using FIGS. 21A to 21D, a detailed explanation of the data structure ofthe video file and an explanation of an additional recording method bypartial erasing or video recording will be given. A block of informationrecorded continuously for a VOB in a video file on the informationstorage medium is expressed in extents as with the UDF. In FIG. 21A,each of VOB #1 and VOB #2 is composed of one extent (extent #a andextent #b, respectively).

In FIG. 21A, like the files in the dustbin on the PC, cell D has beenspecified by the user for erasure. It is deleted from the PGCinformation of FIG. 10B, so the user cannot see it during playback.However, taking cell D out of the dustbin enables cell D to beregistered in the PGC information of FIG. 10B, which enables the user toreproduce it again.

When the first portion of cell B in FIG. 21A is specified by the userfor complete deletion, the MPU of FIG. 11, receiving the complete deleterange of the portion from the user in the form of time information (asto from what second to what second the portion is deleted completely),refers to the cell VOBU table 1117 of FIG. 20 and determines which VOBUthe relevant time range corresponds to.

Next, the VOBU including the boundary time of the complete deletion (thefourth VOBU from the head in cell B corresponds to that VOBU in FIG.21A) is removed from the objects of complete deletion. By this method,the MPU of FIG. 11 calculates the VOBU to be deleted completely anddeletes the relevant portion as shown in FIG. 21B.

Thereafter, when receiving information that the user wants to record avery large amount of information additionally, the MPU of FIG. 11 mapsall the AV addresses in the video file and deletes the AV addresses forthe already recorded portions from the positional information about theVOB of FIG. 22. Then, the addresses for the unrecorded areas are foundfrom the remaining AV addresses. The sizes of all the unrecorded areasare totaled and the result is compared with the additional recordingvideo information size previously specified by the user.

If the totaled size of all the unrecorded areas is insufficient, thedelete-specified area is erased completely as shown in FIG. 21C. If thesize is still insufficient, the delete/overwrite priority rankinformation 2037 is read from the cell time general information 1116 ofFIG. 20 and deleting is done, starting at the highest level of priority.

As a result, the data in VOB #3 is filled into the blank unrecorded areaas shown in FIG. 21D. In FIG. 21D, cell E is divided and recorded in twoseparate places. In FIG. 21D, the data in VOB #3 is divided into threeextents (extent #c, extent #d, extent #e), which are then recorded.

FIG. 22 shows the data structure of the VOB control information 1106 ofFIG. 3F. The VOB control information 1106 is made up mainly of thepositional information on VOBs and information indicating therelationship between pieces of cell information for each VOB. As shownin FIGS. 21A to 21D, one VOB can be distributed over a video file.

A block of information recorded continuously in a video file in a VOB isexpressed by extents as in the UDF. Since the AV address size in thevideo file is known beforehand, when the positional information on allthe VOBs of FIG. 22 is deleted from the mapping of all the AV addresses,the remaining AV addresses are for the unrecorded areas in the videofile.

The various operations of the information reproducing apparatus orinformation recording/reproducing apparatus will be explained.

◯ Processing when the User has Deleted the Recording/Reproducing VideoData by Mistake

After an information storage medium (an optical disk 1001) is installed,the information recording/reproducing section 32 reproducesrecording/reproducing video management data RWVIDEO_CONTROL.IFO.Thereafter, it retrieves recording/reproducing video dataRWVIEO_OBJECT.VOB, still picture data RWPICTURE_OBJECT.POB, thumbnailpicture data RWTHUMBNAIL_OBJECT.POB, and audio data RWAUDIO_OBJECT.AOBon the assumption that the user has deleted the recording/reproducingvideo data by mistake. If some data item is missing, the DVD videorecorder display section 48 is caused to display the message “A specificfile is not found.”

◯ Video File Size Setting Method at the Beginning

A new information storage medium (an optical disk 1001) is installed forthe first time and the information recording/reproducing section 32reproduces recording/reproducing video management dataRWVIDEO_CONTROL.IFO. Finding that recording/reproducing video dataRWVIDEO_OBJECT.VOB has not been created, the MPU causes the DVD videorecorder display section 48 to display the message “A video recordablearea is going to be created. How many hours of video recording do youwant to set for standard setting?” and requests the user to answer. Onthe basis of the answer from the user, the MPU calculates the video filesize automatically and registers a file for recording/reproducing videodata RWVIDEO_OBJECT.VOB in the UDF.

◯ Address Conversion Between LBN and AV Address is Carried Out Using theDMA Information

When a DVD-RAM is used as an information storage medium, the DMA area isread and address conversion between LBN and AV address is carried out. Ameans for reading defect position information from the informationstorage medium corresponds to the information recording/reproducingsection 32 of FIG. 11. A conversion means for effecting addressconversion between logical address and AV address from the defectiveposition information obtained by the means for reading defectiveposition information corresponds to the MPU of FIG. 11.

◯ Interlocking Process of UDF and AV Address According to the Video FileSize Change

As shown in FIG. 19D, as video recording is repeated, the initially setvideo file size may have to be changed. As a means for creating filesystem change information according to the video file size change, theMPU of FIG. 11 calculates change information in the UDF. Then, it causesthe information recording/reproducing section 32 to record the result ofthe calculation on the information storage medium (optical disk 1001).The MPU also functions as a means for creating change information on theAV address setting state in the video file according to the file systemchange information. It causes the information recording/reproducingsection 32 to record the created change information in therecording/reproducing video management data RWVIDEO_CONTROL.IFO of FIG.4 on the information storage medium.

◯ Reallocating Cells/VOB Addresses as a Result of the Video File SizeChange

The MPU of FIG. 11 further functions as a means for creating file systemchange information according to the video file size change. Theinformation recording/reproducing section 32 corresponds to a means forchanging (rewriting) at least part of the address information about thecells recorded on the information storage medium or the addressinformation about VOBs according to the file system change information.

◯ Determining the Unrecorded Position on the Disk from the Cell or VOBAddress Allocation Information

This operation is the same as explained in FIG. 22. A means for readinginformation on a set of the begin address and cell size for each VOB oreach cell or on a set of the begin address and end address from theinformation storage medium corresponds to the informationrecording/reproducing section 32 of FIG. 11. A means for extracting theaddress for the unrecorded area in the video file from the read addressinformation for each VOB or the read address information for each cellcorresponds to the MPU.

◯ Executing a Permission Process According to the Permission Setting inCells or VOBs

Video files containing at least video information and management filesare recorded on an information storage medium. For the video files,information is recorded in files. The information recorded in the filescan be read by playback. The management files have managementinformation about a control method of reproducing the video informationrecorded in the video files.

The video information in the video files contains blocks of informationin cells or VOBs. In the information storage medium, the permissionsetting information is recorded in the management files in cells orVOBs.

A means for reproducing the permission information from the informationstorage medium corresponds to the information recording/reproducingsection 32. The MPU functions as a display control means for providingdisplay control of reproduced pictures according to the reproducedpermission information. In addition, a recording/deleting means forrecording and deleting pictures on the basis of the reproducedpermission information also corresponds to the MPU.

◯ Changing the Size of Cells or VOBs on the Basis of the VOBU Unit

The MPU of FIG. 11 functions as a first judging means for judging thecell or VOB related to the video portion to be deleted when part of thevideo information in the video file is deleted. Using the cell VOBUtable 1117 of FIG. 20, the MPU judges all the VOBUs constituting thecells or VOBs extracted by the first judging means (MPU).

A first decision means (MPU) and a recording means for changing andrecording the recording/reproducing management data by changing the VOBUinformation constituting the cells or VOBs on the basis of the resultfrom the first decision means (MPU) correspond to the informationrecording/reproducing section 32 of FIG. 11. The first decision meansjudges the VOBU corresponding to the picture portion to be deleted andremoves from the VOBUs to be deleted the VOBU in which the boundaryposition of the picture portion to be deleted coincides with the centralposition. For the cells or VOBs judged by the first judging means (MPU),the first decision means removes the VOBU to be deleted judged by athird judging means (MPU) from the VOBUs constituting the cells or VOBsjudged by the second judging means (MPU).

With the embodiment, use of only one video file recordable andreproducible on an information storage medium enables the user to beinformed of abnormality at the beginning of or before playback when theuser has deleted a video file by mistake. With the conventional DVDvideo disk which allows more than one video file to exist, when the userhas deleted one of the video files by mistake, the informationreproducing apparatus or information recording/reproducing apparatusstarts playback without sensing the mistake. It does not display themistake until starting to reproduce the deleted video file. This causesinconvenience to the user. The present invention eliminates thisproblem.

Each of the information reproducing apparatus and informationrecording/reproducing apparatus accesses only the video file(RWVIDEO_OBJECT.VOB of FIG. 4) whose file name has been specified inrecording and reproducing video information. Therefore, even if the userhas put a similar video file (under subdirectory RWV_TS) by mistake, aserious adverse effect can be avoided because each of the informationreproducing apparatus and information recording/reproducing apparatusignores the file.

Only one recordable, reproducible video file is allowed to exist on aninformation storage medium and all the video information recorded in thevideo file is set by a single PGC so that all the video information maybe reproduced in sequence. This makes it easy for the user familiar withthe way of recording a single tape, such as a VTR tape to use theapparatus.

The above method makes it easy to display all the recorded videoinformation in such a manner that all the video information is a stringof information like a single tape. Moreover, the method enables the userto operate the apparatus as if to record, delete, or reproduce the datain a specific place on a single tape.

As a result of allowing an unrecorded area to be defined in the videofile, the following can be done:

(a) The deleted place can be changed to an unrecorded area withoutdecreasing the video file size, when part of the data in the file isdeleted.

(b) Additional data can be recorded in an unrecorded area in the filewithout changing the total file size.

As a result, the video file size need not be changed each time part ofthe video information is deleted or additional video information isrecorded. This enables the data to be written only in the portion to bechanged, such as the deleted place or the additional data recorded placein the unrecorded area, without modifying the portion not to be changedin the video file.

When the contents of a video file of a very large size are changed, theprocess, related to the invention, of changing the data only in theportion to be changed in the video file shortens remarkably the timerequired to change the data on the information storage medium, ascompared with the conventional method of recording all the files again.

Use of unrecorded areas in a video file and playback sequenceinformation (PGC) about all the video information reproducible in thevideo file makes it possible to set a video information recording placein the video file on the application software side that processes thevideo file, independent of the file system (UDF). As a result, a videoinformation recording place can be set according to the playbacksequence information (PGC), which makes it easy to record and reproducethe video information continuously.

The file system, such as the UDF or FAT, is allowed to set the recordingplaces (recording addresses: LBNs (Logical Block Numbers)) of theindividual files. However, since the UDF or FAT is given only the finenames and file sizes, it allocates sequentially the recording positionsof the file sizes given to the blank areas on the information storagemedium.

Specifically, since no PGC information is given to the UDF or FAT,recording places suitable for the continues recording or reproducing ofvideo information cannot be set. Giving an unrecorded area in the videofile makes it unnecessary to change the video file size when part of thevideo information is deleted or a small amount of video information isadded.

As a result, on the file system, such as the UDF or FAT, the recordingplace (recording address) of the video file is not changed in adding asmall amount of video information or deleting part of the videoinformation. The recording place of the additional video information orthe partially deleted place can be managed on the application softwareside that processes the video file.

Specifically, the application software side tells the file system side,such as the UDF, about the LBNs for the place in which partial deletionor overwriting is to be effected and carries out a partial rewritingprocess. Having the playback sequence information (PGC) about all thevideo information reproducible in the video file, the applicationsoftware side can specify addresses that allow continues recording andreproducing of the video information according to the PGC information.

Only one video file is allowed to exist on an information storage mediumand an unrecorded area can be defined in the video file. As a result,even when a video file in which video information is recorded and acomputer file in which general computer data is recorded are allowed toexist on the same information storage medium in a mixed manner, thevideo information can be concentrated and recorded in a specific placeon the information storage medium, which makes it easy to record andreproduce the video information continuously.

Consider a case where a video file and a computer file are recorded onthe same information storage medium in a mixed manner. Addresses (LBNs)indicating the recording places on an information storage medium forcomputer files are set on a file system, such as the UDF. As a result,computer files may be scattered over the information storage medium.

Thereafter, when the video file is recorded, the video file may beentered as a collection of extents separated away from each other insuch a manner that they are interspersed between the scattered computerfiles. In the case of the conventional file structure with no unrecordedarea in a file, the video file size is changed each time part of thevideo information in the file is deleted or additional video informationis recorded. Whenever the video file size changes, the allocationsindicating the recording places on the information storage medium (thedistribution of extents in which the video file is recorded) change.

For example, a very-large-sized video file (to the allocation descriptorof whose file entry consecutive addresses are allocated) is created byhours of video recording in such a manner that the video file islocalized in one place on the information storage medium. Thereafter,when the middle of the recorded video information is deleted, thepartial deletion separates the allocations of the video files into twoplaces on the information storage medium when the file has no unrecordedarea as in the prior art.

Thereafter, PC data may be recorded in the deleted portion. When thevideo file size is made larger by video recording after the PC data hasbeen recorded in the place, additional video information has to berecorded in a position far away from the recording area of the existingvideo file on the information storage medium. The interspersing of asingle video file in separate positions on the information storagemedium has an adverse effect on the continues recording and reproducingof the video information.

With the present invention, securing an unrecorded area in the samevideo file prevents the recorded positions of the video file on theinformation storage medium from interspersing even when partial deletionand additional video recording are repeated. This makes it easy torecord and reproduce the video information continuously.

Since the begin address and size information for each cell or VOB arerecorded together on an information storage medium, the cell (or VOB)allocation distribution in a video file can be sensed at high speed. Asa result, the location of the unrecorded area in the video file can besensed immediately.

This speeds up a series of video recording start processes ofreproducing the management data (RWVIDEO_CONTROL.IFO in FIG. 4), sensingthe unrecorded place in the video file, and starting video recording.When each piece of video information is contained in a separate videofile as in the example of FIG. 1, there is no unrecorded area in thevideo file. Only when a method of containing all the video informationrecorded on an information storage medium in a single video file is usedas in the present invention, an unrecorded area appears in the videofile and information on the allocation distribution of cells in thevideo file is needed.

Since the correlation between AV addresses and LBNs changes as the videofile size changes, the addresses of the cells and VOBs have to bechanged partially. Since the address information about the cells andVOBs recorded in the cell time general information and VOB controlinformation is written as a set of each begin address and size, eachbegin address has only to be changed when the addresses are changed.This reduces the amount of changed management data items.

In the DVD video disk standard, the begin address and end address for acell piece are recorded in the video title set cell piece VTS_CPI in thevideo title set address table VTS_C_ADT. In this case, when addressesare changed, both the begin address and the end address must be changed.With the above method, the cell size or VOB size need not be changed,which reduces the number of changed places by half.

Permission can be set closely in cells or VOBs. In the DVD video diskstandard, the parental lock function is carried out on a video titlebasis or a PGC basis. With the UDF, permission can be set file by file.

With the present invention, since there are a single video file and aPGC covering all the video information on an information storage medium,neither the close setting of permission according to the videoinformation nor the setting of parental lock nor security management canbe effected. However, the invention provides permission setting flagsfor each cell or each VOB, enabling the close setting of permission.

The cell size or VOB size is changed on a VOBU basis as a result ofpartial deletion of the video information, which makes re-encodingunnecessary. Only the management data (e.g., RWVIDEO_CONTROL.IFO) has tobe changed, speeding up the change operation.

Since conventional DVD video disks are for playback only, the cell sizeor VOB size need not be changed by partial deletion of the videoinformation. Video-recordable information storage mediums of the presentinvention, however, require the change of the cell size or VOB size. Ascompared with a case where the VOBU is created again (re-encoded) eachtime the cell size or VOB size is changed, the method of the presentinvention enables the cell size or VOB size to be changed easily at highspeed.

Since a VOB on the information storage medium can be recorded over acluster (extent) of one or more video recording areas, the VOB can berecorded over a cluster (extent) of plural blocks of video informationin such a manner that it intersperses between the pieces of videoinformation scattered in the video file.

With the data structure of the information storage medium of theinvention, since all the video information is recorded in a single videofile, pieces of recorded video information are scattered in the videofile as video recording and partial deletion are repeated many times. Asa result, many small-sized unrecorded areas are scattered in the videofile.

When VOBs are recorded in consecutive address areas, places in whichlarge VOBs can be recorded are limited, reducing the recordable capacityof the video file. By enabling a single VOB to be recorded over acluster (extent) of plural video areas separate from each other in thevideo file, video recording can be done without wasting many small-sizedunrecorded video areas scattered in the file.

FIGS. 23A to 23H illustrate another example of a hierarchical structureof the information recorded on an optical disk 1001 serving as aninformation storage medium. FIGS. 23A to 23C correspond to FIGS. 3A to3C explained earlier. The contents of the audio & video data area 1009in FIG. 23C correspond to those of the audio & video data area 1009 inFIG. 3C as described below.

The navigation data RTR_VMG 2201 in FIG. 23D corresponds to the controlinformation 1011 in FIG. 3D. The movie video recording objectRTR_MOV.VRO 2202 in FIG. 23D corresponds to the video object 1012 inFIG. 3D.

The still picture video recording object RTR_STO.VRO 2203 in FIG. 23Dcorresponds to the picture object 1013 in FIG. 3D. The stillpicture-added video recording object RTR_STA.VRO 2204 in FIG. 23Dcorresponds to the audio object 1014 in FIG. 3D.

Neither the maker specification object MSP.VOB 2205 nor other streamobject AST.VOB 2206 in FIG. 23D is shown in FIG. 3D. In the explanation,RTR is an abbreviation of real time recording.

The navigation data RTR_VMG 2201 is used to record, reproduce, or editan AV stream (one or more video object set VOBS). The navigation dataRTR_VMG 2201 contains all the necessary navigation data including asingle management information file called RTR_IFO.

Specifically, as shown in FIG. 23E, the navigation data RTR_VMG 2201includes RTR video manager information RTR_VMGI 2210, a movie AV fileinformation table M_AVFIT 2211, a still picture AV file informationtable S_AVFIT 2212, an original PGC information ORG_PGCI 2213, auser-defined PGC information table UD_PGCIT 2214, a text data managerTXT_DT_MG 2215, and a manufacturer information table MNFIT 2216.

These seven types of information 2210 to 2216 are written in the fileRTR_IFO in the order in which they have been described above. Most ofthe information written in the file RTR_IFO is stored in the RAM of themicrocomputer block 30 of FIG. 11.

In the RTR video manager information RTR VMGI 2210, the basicinformation (similar information to the video manager information VMGIin the DVD video ROM) on the RTR disk (optical disk 1001) is written. Inthe movie AV file information table M_AVFIT 2211, a movie AV filecorresponding to the movie video recording object RTR_MOV.VRO of FIG. 24is written.

In accordance with the AV data control information 1101 in the controlinformation 1011 of FIG. 3D, the navigation data RTR_VMG 2201 of FIG.23D includes a movie AV file information table M_AVFIT 2211.

As shown in FIG. 23F, the movie AV file information table M_AVFIT 2211includes a movie AV file information table M_AVFITI 2220, one or morepieces of movie VOB stream information M_VOB_STI #1 TO M_MOB_STI #n2221, and movie AV file information M_AVFI 2222.

In the movie AV file information M_AVFI 2222, information on the movieAV file whose file name is movie video recording object RTR_MOV.VRO iswritten.

As shown in FIG. 23G, the movie AV file information M_AVFI 2222 includesgeneral information M_AVFI_GI 2230 in the movie AV file informationM_AVFI, one or more movie VOB information search pointers M_VOBI_SRP #1to M_VOBI_SRP #n 2231, and one or more pieces of movie VOB informationM_VOBI #1 2232 to M_VOBI #n 2233.

An n number of pieces of movie VOB information M_VOBI #1 2232 to M_VOBI#n 2233 in the movie AV file information M_AVFI 2222 are written in thesame order in which the VOB data items stored in the move AV file.

As shown in FIG. 23H, each of the pieces of movie VOB information M_VOBI#1 2232 to M_VOBI #n 2233 includes movie VOB general information MVOBI_GI 2240, seamless information SMLI 2241, audio gap informationAGAPI 2242, and time map information TMAPI 2243. The time mapinformation TMAPI 2243 includes the cell general time information 1116and cell VOBU table 1117 shown in FIG. 3H.

FIG. 24 shows an example of a directory structure of the information(data file) recorded on an optical disk 1001 using the data structureshown in FIGS. 23A to 23H. Even when the optical disk 1001 and itsreproducing apparatus use the data structure shown in FIGS. 23A to 23H,the user cannot see the data structure. The data structure the user canperceive is a hierarchical file structure as shown in FIG. 24.

Specifically, according to the types of data recorded in the data area1004 of FIG. 23B, the DVD_RTR directory, VIDEO_TS directory, AUDIO_TSdirectory, and computer data file directories are displayed in the formof menu screens or icons on the root directory screen (not shown).

The DVD_RTR directory of FIG. 24 corresponds to the RWV_TS file of FIG.4. Under the DVD_RTR directory, the following have been stored: the fileRTR.IFO for navigation data RTR_VMG of FIG. 23D, a backup file RTR.BUPfor the RTR.IFO, a file RTR_MOV.VRO for the movie video objectRTR_MOV.VOB, a file RTR_STO.VRO for the still picture video objectRTR_STO.VOB, a file RTR_STA.VRO for the still picture-added audio objectRTR_STA.VOB, a file MSP.VOB for the maker specification object, and afile AST.SOB for other stream objects.

The file RTR_IFO shall exists as long as any contents compliant to thisspecification are recorded. The navigation data is recorded in the fileRTR_IFO.

Since the stream data categorized in movie VOB are recorded in the fileRTR_MOV.VRO. Therefore, as long as any movie VOB exist, this file shallexist.

The stream data categorized in still picture VOB are recorded in thesetwo files RTR_STO.VRO and RTR_STA.VRO. The file RTR_STO.VRO is used torecord original VOBs which consists of a video part including anoptional sub-picture unit an optional audio part associated with thevideo part.

The file RTR_STA.VRO is used to record additional audio part whichrepresents an audio stream recorded in after recording. The audio partrecorded in the file RTR_STA.VRO shall be used in combination with someof the video part recorded in the file RTR_STO.VRO.

The file RTR_STO.VRO shall exist as long as any still picture VOBexists, and file RTR_STA.VRO shall exist as long as any additional audiopart to be presented with some video part recorded in the fileRTR_STO.VRO exists.

Among other PGCs, only original PGC includes stream data stored in thefile VRO. Then, only one original PGC shall exist in the disk.

The user-defined PGC is a chain of part of programs. However, itcontains only navigation data and each part of program refer to streamdata belonging to the original PGC. Therefore, creating or deleting anuser-defined PGC does not affect the original PGC at all.

A VOBU is a basic unit of a VOB which consists of one or more GOPs ofvideo data. It has a presentation time period between 0.4 seconds to 1second is case of movie VOB. In case of still picture VOB, a VOBUcontains only one video picture, and the whole VOB becomes a VOBU.

There is an exceptional rule that the last VOBU of a movie VOB may havea presentation time period less than 0.4 seconds period.

A cell in the original PGC is called original cell. A cell in theuser-defined PGC is called user-defined cell. The two types of cells aredefined each for movie VOB and still picture VOB. When the cell type isfor movie VOB, the cells shall only refer to a whole or a part of themovie VOB.

The PGCI is a data structure to represent a total presentation of a PGC.This is used both for the original PGC and user-defined PGC. Theuser-defined PGC has only PGCI. The cells in the PGCI refer to VOBs inthe original PGC. The total presentation of the PGC is described as apresentation sequence of cells defined in the PGCI.

The original PGC consists of PGCI, VOBI, and VOB. The PGCI consists ofeither one cell or a sequence of more than one cell. Therefore, thetotal presentation of the original PGC is a sequence of cellpresentation. The cell presentation order is the same as the order ofwhich cell information is described in the PGCI.

The most noticeable characteristic of the present invention lies in theoriginal PGC. Specifically, the original PGC shows the procedure ofreproducing all the video data items in the RTR_MOV.VRO of FIG. 24 insuch a manner that they are linked to each other as if they were asingle tape. Moreover, the original PGC contains not only all the videodata items in the RTR_MOV.VRO but also all the still picture informationin the RTR_STO.VRO and all the additional audio information in theRTR_STA.VRO and shows the playback procedure in such a manner that allthe pieces of information are related to each other as if they were anintegral single tape. This enables all the data items to be reproducedconsecutively.

In order to enable presentation of each cell, the cell informationincludes VOB numbers, presentation start time, and presentation endtime.

In the original PGC, each cell refers to the presentation period of awhole VOB. So presentation start time and presentation end time of acell becomes equal to the presentation time of the first video pictureof the VOB and the presentation time of the last video picture of theVOB, respectively.

In order to access to a VOB recorded in a VOB file, VOBI is used toobtain address information with respect to the file. Especially in orderto access to a middle of VOB data when a special play like time searchis performed, VOBI includes a time map (TMAP). The TMAP is a conversiontable from a given presentation time inside the associated movie VOB tothe address of the associated VOBU inside the VOB.

When a VOB is created, it is appended at the end of the VOB file and anassociated cell and possibly an associated program is appended at theend of the PGCI.

FIG. 25 conceptually illustrates a case where the user has changed thecell playback sequence of the contents of the original video recording(original PGC) later, using the user-defined PGC. For example, the videodata (video object set VOBS) recorded in the audio & video data area1009 of FIG. 23C is composed of a collection of one or more programchains PGCs.

Each PGC is a collection of programs made up of one or more cells. Inwhat sequence which cells are to be reproduced to create a program canbe determined by the original PGC information ORG_PGCI 2213 oruser-defined PGC information table UD_PGCIT 2214 of FIG. 23E.

The table TMAP in the time map information TMAPI 2243 of FIG. 23Hconverts the playback time and playback sequence of the cells specifiedin the original PGC information ORG_PGCI 2213 or user-defined PGCinformation table UD_PGCIT 2214 into addresses for VOBUs constitutingthe cells to be reproduced.

Specifically, when reproducing is done by the original PGC (the cellplayback sequence in the initial video recording state), the addressesfor the VOBUs for the time zone to be reproduced via the time mapinformation table TMAP are determined on the basis of the contents ofthe original PGC information ORG_PGCI 2213 of FIG. 23E. Then,reproducing is done in the order of the determined addresses.

On the other hand, when reproducing is done by the user-defined PGC(when the user has edited the playback sequence after video recording),the addresses for the VOBUs for the time zone to be reproduced via thetime map information table TMAP are determined on the basis of thecontents of the user-defined PGC information table UD_PGCIT 2214 of FIG.23E. Then, reproducing is done in the order of the determined addresses.

The cell playback sequence by the user-defined PGC information tableUD_PGCIT 2214 may be made completely different from the cell playbacksequence by the original PGC information ORG_PGCI 2213. The playbacktime can be correlated to the addresses of the VOBUs to be reproduced,referring to the contents of the time entry and VOBU entry in the timemap information TMAPI.

As shown in FIG. 26, the original PGC can be composed of programs. Inthis case, for example, programs may be divided into programs differingin video recording time.

The operation of reproducing the original PGC composed of movingpictures proceeds as follows:

1. Obtain file system information by reading the disk and open the filesRTR.IFO and RTR_MOV.VRO.

2. Read the entire file RTR.IFO into the memory and examine the PGCI.

3. Examine file system information of the file RTR_MOV.VRO to obtain thefile extents where the addresses and sizes regarding the VOB dataallocations are described.

4. For each cell in the PCCI starting from one having the earliest cellnumber, get the VOBI using the VOB number associated with the cell, andfind corresponding TMAP in the VOBI in order to convert presentationstart time and presentation end time to the address offsets in the fileVRD.

5. Start reading the VOB data from the file and perform initialbuffering until some amount of the VOB data are buffered in the trackbuffer. The initial buffering is needed whenever the reading encountersa nonseamless cell boundary.

6. Start decoding the VOB data being buffered in the track buffer andkeep reading and decoding until the cell has been completely presented.

7. Loop to step 5 until all of the cells in the original PGC have beencompletely presented.

Next, the program chain information PGCI contains the navigationinformation for program chains PGCS. There are two types of programchains defined in this specification, the original PGCs and user-definedPGCs. Original PGC has VOBs as well as PGCI. However, the user-definedPGC does not have its own VOBs but refer to the VOBs in the originalPGC.

As shown in FIG. 27, the program chain information PGGI includes PGCgeneral information PGC_GI, one or more pieces of program informationPGI #1 to PGI #m, one or more cell information search pointers CI_SRP #1to CI_SRP #n, and one or more pieces cell information CI #1 to CI #n.

As shown in FIG. 28, the PGI general information PGC_GI includes onebyte of reservation, one byte of PG_Ns, two bytes of CI_SRP Ns. PG_Nsdescribes the number of programs in the PGC. In user-defined PGCs, 0 isset in PG_Ns. The maximum number of programs in the original PGC is 99.The CI_SRP_Ns describes the number of cell information search pointersin the PGC. The maximum number of cells in the PGC is 999.

As shown in FIG. 29, the program information PGI includes one byte ofreservation, one byte of PG_TY, two bytes of C_Ns, 128 bytes ofPRM_TXTI, two bytes of IT_TXT_SRPN, and 8 bytes of THM_PTRI.

The PG_TY describes the type of the program. As shown in FIG. 30, whenthe protect bit b7 is 0, this means that the program is not protected.When the protect bit b7 is 1, this means that the program is protected.When a program is in protected state, all the VOBs referred and utilizedin the presentation of that program shall not be temporarily orpermanently erased. The protect flag shall not be set to 1 unless allthe VOBs referred by this program are in normal state.

The C_Ns describes the number of cells in the program.

The PRM_TXTI describes primary text information for the program. Thefirst 64 bytes of the 128 bytes field is used to describing primary textin ASCII character set. If the primary text in ASCII is shorter than 64bytes, the remaining bytes shall filled with 00h.

The last 64 bytes of the 128 bytes field is used for describing primarytext in another character sets, like so called shift JIS or ISO 8859-15.Another character set code is described in VMGI_MAT and shared by allthe primary text information in the disk. The terminal control codes,which take values in the range from 01h to 11h, shall not be describedin PRM_TXTI.

The IT_TXT_SRPN describes the number of IT_TXT_SRPs in IT_TXT whose textdata corresponds to the program.

The THM_PTRI describes thumbnail pointer information. Setting and usingthe thumbnail pointer information is an optional function for bothrecorders and players. Recorders which don't have capability to handlethis information may set FFh to all eight bytes of THM_PTRI. Playerswhich don't have capability to handle this information may simplyignores the information.

As shown in FIG. 31, the THM_PTRI includes two bytes of CN and six bytesof THM_PT. The CN describes the cell number in which the thumbnail pointexists. The THM_PT describes the thumbnail point in the target cell.When the resume marker exists in a movie cell, the THM_PT describes apresentation time PTM.

When the thumbnail exists in a still picture cell, the THM_PT describesthe still picture VOB entry number S_VOB_ENTN in the corresponding stillpicture VOB group S_VOG shown in FIG. 32.

The cell information search pointer CI_SRP of FIG. 27 includes fourbytes of CI_SA as shown in FIG. 33. The CI_SA describes the startaddress of CI with RBN from the first byte in the PGCI.

The cell information CI of FIG. 27 has two types, movie cell informationM_CI and still picture information S_CI as shown in FIG. 34.

The movie cell information M_CI is composed of movie cell generalinformation M_C_GI as shown in FIG. 35. As shown in FIG. 36, the moviecell general information M_C_GI includes one byte of reservation, onebyte of C_TY, two bytes of M_VOBI_SRPN, two bytes of C_EPI_Ns, six bytesof C_V_S_PTM, and six bytes of C_V_E_PTM.

The C_TY describes the type of the cell. As shown in FIG. 37, 000b iswritten in three bits b7 to b5 in the C_TY1 for movie cells. TheM_VOBI_SRPN describes the number of movie VOBI search pointersM_VOBI_SRPs related to the movie cells. The C_EPI_Ns describes thenumber of pieces of cell entry point information C_EPIs.

The C_V_S_PTM describes the playback start time in the PTM descriptionform in the RTR. The C_V_S_PTM and C_V_E_PTM fulfill the followingrequirements:

(1) In case of a cell in the original PGC, the C_V_S_PTM shall fall intothe first four VOBUs of the corresponding VOB and the C_V_E_PTM shallfall into the last four VOBUs of the corresponding VOB.

(2) In case of a cell is in an user-defined PGC, the following relationhas to be fulfilled:

O_C_V_S_PTM≦C_V_S_PTM≦C_V_E_PTM≦O_C_V_E_PTM

where O_C_V_S_PTM and O_C_V_E_PTM are the presentation start time andend time of the original cell which corresponds to the VOB referred bythis cell.

The O_V_E_PTM describes the presentation end time of the cell in RTR'sPTM describing format.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A machine readable information recording medium for access by aninformation reproducing apparatus, the information recording mediumembodied as an optical disc comprising: a first area in which a videoobject is recorded, the video object including a video object unit, thevideo object unit having a presentation time between 0.4 seconds and 1.0second, the video object unit containing a VOBU begin pack placed at atop of the video object unit, the VOBU begin pack having recording timeinformation on the video object unit, and the recording time informationbeing expressed in year, month, day, hour, minute, and second; and asecond area in which control information is recorded, the controlinformation including first program chain information and second programchain information, the first program chain information relating to afirst program chain, the second program chain information relating to asecond program chain, cells being specified by the control information,the first program chain specifying a first presentation sequence of onepart of the cells, the second program chain specifying a secondpresentation sequence of another part of the cells, a first cell of theone part of cells referring to a first region of the video object, asecond cell of the another part of cells referring to a second region ofthe video object, a part of the first region being able to overlap withthe second region, and another part of the first region being able notto include the second region, and wherein the control information isread and provided to reproduce the video object by the informationreproducing apparatus, and the video object is accessed according to theread control information.
 2. An information reproducing method forreproducing information from an information recording medium, theinformation recording medium having a first area in which a video objectis recorded, the video object including a video object unit, the videoobject unit having a presentation time between 0.4 seconds and 1.0second, the video object unit containing a VOBU begin pack placed at atop of the video object unit, the VOBU begin pack having recording timeinformation on the video object unit, and the recording time informationbeing expressed in year, month, day, hour, minute, and second, and asecond area in which control information is recorded, the controlinformation including first program chain information and second programchain information, the first program chain information relating to afirst program chain, the second program chain information relating to asecond program chain, cells being specified by the control information,the first program chain specifying a first presentation sequence of onepart of the cells, the second program chain specifying a secondpresentation sequence of another part of the cells, a first cell of theone part of cells referring to a first region of the video object, asecond cell of the another part of cells referring to a second region ofthe video object, a part of the first region being able to overlap withthe second region, and another part of the first region being able notto include the second region, and the information reproducing methodcomprising: reading the control information; and accessing andreproducing the video object based on the read control information. 3.An information recording method for recording information on aninformation recording medium, the information recording medium having afirst area in which a video object is recorded, the video objectincluding a video object unit, the video object unit having apresentation time between 0.4 seconds and 1.0 second, the video objectunit containing a VOBU begin pack placed at a top of the video objectunit, the VOBU begin pack having recording time information on the videoobject unit, and the recording time information being expressed in year,month, day, hour, minute, and second, and a second area in which controlinformation is recorded, the control information including first programchain information and second program chain information, the firstprogram chain information relating to a first program chain, the secondprogram chain information relating to a second program chain, cellsbeing specified by the control information, the first program chainspecifying a first presentation sequence of one part of the cells, thesecond program chain specifying a second presentation sequence ofanother part of the cells, a first cell of the one part of cellsreferring to a first region of the video object, a second cell of theanother part of cells referring to a second region of the video object,a part of the first region being able to overlap with the second region,and another part of the first region being able not to include thesecond region, and the information recording method comprising:recording a new video object on the first area; and adding new controlinformation to the second area.
 4. An information reproducing apparatusfor reproducing information from an information recording medium, theinformation recording medium having a first area in which a video objectis recorded, the video object including a video object unit, the videoobject unit having a presentation time between 0.4 seconds and 1.0second, the video object unit containing a VOBU begin pack placed at atop of the video object unit, the VOBU begin pack having recording timeinformation on the video object unit, and the recording time informationbeing expressed in year, month, day, hour, minute, and second, and asecond area in which control information is recorded, the controlinformation including first program chain information and second programchain information, the first program chain information relating to afirst program chain, the second program chain information relating to asecond program chain, cells being specified by the control information,the first program chain specifying a first presentation sequence of onepart of the cells, the second program chain specifying a secondpresentation sequence of another part of the cells, a first cell of theone part of cells referring to a first region of the video object, asecond cell of the another part of cells referring to a second region ofthe video object, a part of the first region being able to overlap withthe second region, and another part of the first region being able notto include the second region, and the information reproducing apparatuscomprising: a reading unit configured to read the control information;and an accessing unit configured to access and to reproduce the videoobject based on the read control information.